Field of the Invention
This invention relates generally to static gaskets of the type used to establish a fluid-tight seal between two members to be clamped together, and more particularly to multilayer static gaskets clamped between a cylinder head and an engine block in an internal combustion engine.
Related Art
When establishing a fluid-tight seal between two members to be clamped together, such as between a cylinder head and an engine block, it is common in certain high-temperature applications to use a static gasket having multiple layers. Generally, at least one of the layers of the multilayer gasket, sometimes referred to as a functional layer, has an embossed sealing bead that is flattened when compressed between the two opposing members. This compressible sealing bead helps to establish a fluid-tight seal. The gasket may include more than one functional layer and/or one or more so-called distance layers. Distance layers are configured to abut one (or more) of the functional layers in an effort to establish a combustion seal by compressing the sealing bead of the functional layer. Unfortunately, while fastening the cylinder head to an engine block, or other applications, damage can occur to the sealing bead in the event of overcompression. If the seal bead is overcompressed and substantially flattened, in addition to losing its ability to exert a high compression sealing pressure, fatigue cracks can form in the area of the sealing bead both during initial clamping and later while in use. Fatigue cracks are particularly undesirable as they ultimately reduce the ability of a static gasket to establish a tight seal, thereby diminishing its life and performance characteristics. To address the overcompression issue, the prior art has taught the use of a compression limiter, or stopper, feature. The compression limiter is most often configured as a solid, substantially incompressible, metallic ring whose height establishes to maximum compressibility of the entire gasket assembly.
US Publication No. 2009/0200752 to Okano, published Oct. 13, 2009 and assigned to the assignee of this invention, describes a multilayer static gasket including a supplemental bead compression limiting feature. The entire disclosure of US Publication No. 2009/0200752 is hereby incorporated by reference and relied upon. While effective, the gasket construction described in this prior document can, in some circumstances, be difficult to manufacture as it may require precision manufacturing processes to achieve subtle differences in stopper heights.
Accordingly, there is a need in the art for an improved multilayer static gasket construction including a bead compression limiting feature and further which is easily manufactured using conventional techniques and relatively low cost materials.